remove invalid JS according to newest spec

which will cause SyntaxError: The left-hand side of a for-of loop may not be 'async'

refer to https://tc39.es/ecma262/#sec-for-in-and-for-of-statements

Author: Archkon

js-quirks.md

@@ -361,7 +361,6 @@ to make it a little less confusing.)
 
     ```js
     for (async of => {};;) {}
-    for (async of []) {}
     ```
 
     In the first line, `async` is a keyword and `of` is an identifier;